Identifying Follicular Regulatory T Cells by Confocal Microscopy

Follicular regulatory T cells are a subset of Foxp3⁺ regulatory T cells that migrate into the B cell follicle after infection or immunization and modulate the germinal center response. The anatomical positioning of follicular regulatory T cells within the germinal center is a defining characteristic of this subset of regulatory T cells; because of this, it is critical that studies of follicular regulatory T cells are able to identify them in situ. In this chapter we describe an immunofluorescence staining method to visualize follicular regulatory T cells in frozen secondary lymphoid tissue sections by confocal imaging.